Software adjustable bed leveling on UMO

youmagine

To adjust your bed just like the Ultimaker 2 you basically have two options. You can either Home Z at the bottom or Home Z at the top using a sensor instead of the home switch to be able to home lower than Z0. For the first solution, look at the following Youmagine mod by NeoTko: https://www.youmagine.com/designs/new-z-endstop-limit-location-for-calibration-a-la-um2-on-umo This design focuses on the second option: using a sensor for Z homing. More information about the setup and firmware can be found here: https://bultimaker.bulles.eu/experimental/ You can also check this thread on the Ultimaker community: https://ultimaker.com/en/community/22120-idea-new-location-for-z-limit-on-umo About the sensor, I am using a SN04 PNP inductive proximity sensor. These sensors are inexpensive and accurate, homing is accurate at 0.01mm. You can use this simple holder to secure the sensor in the holes of the second extruder. The sensor will trigger accurately on the top screw of the bed cap, but you need to add a metallic tape under the screw to ensure that the sensor continues to trigger past the screw! I am leaving the original end-stop switch in place as a safety measure. In any case, the bed won't crash into the hot end. Normally open or closed? These sensors are typically available in two flavors: Normally Open (NO) or Normally Closed (NC). The Ultimaker switch operates as an NO switch. If you use an NO sensor, you can cable it in parallel with the switch. If you decide to use a NC sensor, "re-cable" the Ultimaker switch in NC and re-configure the firmware. From an electrical standpoint, these sensors typically run on a voltage between 12 and 30 volts, the higher the better. You can easily source the 24 volts (or 19 volts) from the 'always on' fan output. Be careful, you cannot inject the sensor signal directly into the AVR microprocessor, use an octocoupler to separate electrically the sensor and your UtliBoard. For clarity, I have indicated the polarity in the pictures.